Converting 90 amp AC welder to DC - Page 9
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  1. #201

    Re: Converting 90 amp AC welder to DC

    I did this mod and my welder will not weld . Just sits there and dims the lights in the house and blows the breaker. Tested everything and it's all good . What did I do wrong

  2. #202
    Join Date
    Oct 2012
    Location
    Sacramento, California
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    1,065

    Re: Converting 90 amp AC welder to DC

    Dafuq?

  3. #203
    Join Date
    Jan 2009
    Location
    Sonoma County
    Posts
    747

    Re: Converting 90 amp AC welder to DC

    Maybe the instructions were for the old blue 90A welders, and you applied them to the current black version?

  4. #204

    Re: Converting 90 amp AC welder to DC

    That's what I did . Is there another way of doing this mod . If so where can I find it.

  5. #205
    Join Date
    Oct 2015
    Posts
    17

    Re: Converting 90 amp AC welder to DC

    Hey guys, if I do the capacitor mod without the bridge rectifier, will the output be a square wave output?

    Sent from my SAMSUNG-SM-N910A using Tapatalk

  6. #206
    Join Date
    Dec 2011
    Location
    Sunny South Florida
    Posts
    112

    Re: Converting 90 amp AC welder to DC

    Quote Originally Posted by Harpman View Post
    Hey guys, if I do the capacitor mod without the bridge rectifier, will the output be a square wave output?

    Sent from my SAMSUNG-SM-N910A using Tapatalk
    No. You must use a bridge. The bridge is what actually changes it from AC to DC. The capacitor just evens out the rectified DC.
    HF 151 Dual Mig Welder (with mods)
    Lincoln 225-S AC Welder
    Buffalo MM-1 Milling Machine
    Craftsman/Atlas 6 inch Metal Lathe
    Buffalo RF-115 4 x 6 inch Band-Saw

  7. #207
    Join Date
    Oct 2015
    Posts
    17

    Re: Converting 90 amp AC welder to DC

    I know. I wanted to to know it the capacitor would give me a square wave ac, for aluminum.

    Sent from my SAMSUNG-SM-N910A using Tapatalk

  8. #208
    Join Date
    Dec 2011
    Location
    Sunny South Florida
    Posts
    112

    Re: Converting 90 amp AC welder to DC

    Quote Originally Posted by Harpman View Post
    I know. I wanted to to know it the capacitor would give me a square wave ac, for aluminum.

    Sent from my SAMSUNG-SM-N910A using Tapatalk
    No....no square wave. Capacitor useless without bridge.

    In fact, since the capacitor is for DC only, it just might explode without the bridge. Don't try it at home!
    HF 151 Dual Mig Welder (with mods)
    Lincoln 225-S AC Welder
    Buffalo MM-1 Milling Machine
    Craftsman/Atlas 6 inch Metal Lathe
    Buffalo RF-115 4 x 6 inch Band-Saw

  9. #209
    Join Date
    Oct 2015
    Posts
    17

    Re: Converting 90 amp AC welder to DC

    Thanks !

    Sent from my SAMSUNG-SM-N910A using Tapatalk

  10. #210

    Re: Converting 90 amp AC welder to DC

    a couple of questions on the upgrade(s):

    - I see most people are going with 8gauge wire for the jumpers to the cap & for the inductor. It would seem that 6gauge should be used given the high amperage of the output, although I realize that it's a relatively short wire run for those parts of the circuit. So, should 8ga be ok? Can anyone confirm that their modded welder with 8ga wiring is holding up, and the wire is not overheating?

    - the stock ground lead looks like it's some odd size, somewhere between 6&8 gauge. Would it worthwhile to upgrade the ground lead (and/or the torch lead) with thicker gauge wire? Or, should the stock leads be ok?

    - If I want to still be able to work on thin stuff/sheet metal, do I simply need to eliminate the cap out of the circuit?

  11. #211
    Join Date
    Oct 2013
    Location
    East Tennessee
    Posts
    28

    Re: Converting 90 amp AC welder to DC

    Sorry to dredge up an old thread. Just finished the conversion with parts that I've had for over a year. 100amp 1000volt rectifier (I feel the 150 amp 3 phase probably are not fully 150 amp on one phase), 2 paralleled 33000 mfd 50 Volt caps. I used 4 AWG for hook up to/from rectifier and through the choke, which is only 12 turns through a ferite ring. Used 6AWG to connect to the caps (flattened 1/4" copper tubing to join them) with the 50 ohm 10 watt ceramic resistor across them. Recitfier is mounted on ~2"x 6" x 1/2" aluminum plate with high-dollar heat paste that I had a bunch of left over. That is mounted under the mid-deck beside the xformer. The choke (on the - to the electrode) is up with the wire feed and tapped into the electrode line there. Caps in front of the xformer on the bottom. A Folgers plastic coffee bucket was cut up and used as a fan shroud, and as extra insurance against undesired shorts.

    Haven't tried it yet, maybe tomorrow if weather holds.
    Last edited by pidjones; 12-12-2018 at 10:15 PM.
    "Love 'em all... let God sort 'em out!"

  12. #212
    Join Date
    Jan 2009
    Location
    Sonoma County
    Posts
    747

    Re: Converting 90 amp AC welder to DC

    We need photos!
    HF MIG-180 with all the mods.
    Grizzly H8153 Stick/Tig Pulse 130/160.
    Wards PowrKraft AC-230. Stick & carbon arc.

  13. #213
    Join Date
    Apr 2016
    Location
    CA
    Posts
    5,917

    Re: Converting 90 amp AC welder to DC

    Quote Originally Posted by California View Post
    We need photos!
    Yeah of the fireworks display . J/k hope it works good and I second the notion of pics and I’ll add an “or it never happened”
    Lincoln, ESAB, Thermal Dynamics, Victor, L-tec, Miller, Dewalt, Makita, Kalamzoo. Hand tools, power tools, welding and cutting tools.

  14. #214
    Join Date
    Oct 2013
    Location
    East Tennessee
    Posts
    28

    Re: Converting 90 amp AC welder to DC

    Corrected my earlier post. Yes, the (-) is to the electrode. Used these to connect to the rectifier. https://uploads.tapatalk-cdn.com/201...bf40303ae1.jpghttps://uploads.tapatalk-cdn.com/201...f01494091a.jpg
    "Love 'em all... let God sort 'em out!"

  15. #215
    Join Date
    Oct 2013
    Location
    East Tennessee
    Posts
    28

    Re: Converting 90 amp AC welder to DC

    Tried it today. Much better than before, but found that I have to cut the wire right at the exit of the torch. This gives a short delay before the wire makes it to the workpiece, giving the cap time to charge. Otherwise, it just sticks to the workpiece and doesn't start arcing. Did a ~2.5" bead without hitting overload. A lot less sputter and better penetration.
    "Love 'em all... let God sort 'em out!"

  16. #216
    Join Date
    Jan 2009
    Location
    Sonoma County
    Posts
    747

    Re: Converting 90 amp AC welder to DC

    Maybe too much capacitor, more than the power supply can feed in that first moment?
    HF MIG-180 with all the mods.
    Grizzly H8153 Stick/Tig Pulse 130/160.
    Wards PowrKraft AC-230. Stick & carbon arc.

  17. #217
    Join Date
    Oct 2013
    Location
    East Tennessee
    Posts
    28

    Re: Converting 90 amp AC welder to DC

    66000 mfd. Shouldn't be too much, but there will be some time constant. Just cutting the stick-out shorter and giving it the time to run out is really easier for me to remember than wait five seconds for the resistor to bleed it down. I didn't check temperatures, and only welded both sides on a 3/16 x 2" cut at a 45. Long piece, and the steel bends while the weld holds even though I missed about 1/2" of it (think the shield was set a little dark for flux MIG).
    "Love 'em all... let God sort 'em out!"

  18. #218
    Join Date
    Oct 2013
    Location
    East Tennessee
    Posts
    28

    Re: Converting 90 amp AC welder to DC

    Name:  64a677fcc3b142bef1731df01494091a.jpg
Views: 175
Size:  50.5 KB
    Sorry it didn't come out right in my previous post.
    "Love 'em all... let God sort 'em out!"

  19. #219

    Re: Converting 90 amp AC welder to DC

    Looks great, but I am thinking a french press was the way to go.

    love the commitment to taking a poor product and making something out of it.

  20. #220

    Re: Converting 90 amp AC welder to DC

    Hopefully somebody is still monitoring this thread. I am doing the mod to your basic HF 90A AC welder to DC. Got 200A rectifier, and a 100,000uf cap, connectors and 8AWG flex wire and also a transformer to run the wire feed motor through the trigger relay. The question I can't seem to get an answer to is about the induction coil or choke. I started asking this on an EE forum site here.

    Naturally the EE folks got very VERY technical and wanted me to calculate the inductance of the coil etc. All I want to know is if I wrap a stripped down toroid core from a power amp with as many wraps of 8AWG wire as I can will that be a worthwhile improvement and is there any reason I should not? I was about to just not do that part of the mod then I somehow happened onto this site which seems a little more user friendly (not that they weren't friendly) for a woodworker like me.

    Yes, I could just buy another welder but where's the fun in that?

    Any help would be much appreciated.
    Last edited by Andybb; 02-01-2019 at 10:20 PM.

  21. #221

    Re: Converting 90 amp AC welder to DC

    I'll also try posting in the main HF thread.

  22. #222
    Join Date
    Oct 2013
    Location
    East Tennessee
    Posts
    28

    Re: Converting 90 amp AC welder to DC

    Quote Originally Posted by Andybb View Post
    Hopefully somebody is still monitoring this thread. I am doing the mod to your basic HF 90A AC welder to DC. Got 200A rectifier, and a 100,000uf cap, connectors and 8AWG flex wire and also a transformer to run the wire feed motor through the trigger relay. The question I can't seem to get an answer to is about the induction coil or choke. I started asking this on an EE forum site here.

    Naturally the EE folks got very VERY technical and wanted me to calculate the inductance of the coil etc. All I want to know is if I wrap a stripped down toroid core from a power amp with as many wraps of 8AWG wire as I can will that be a worthwhile improvement and is there any reason I should not? I was about to just not do that part of the mod then I somehow happened onto this site which seems a little more user friendly (not that they weren't friendly) for a woodworker like me.

    Yes, I could just buy another welder but where's the fun in that?

    Any help would be much appreciated.
    I was able to get 12 turns through the ferrite ring that I bought on ebay. More would be better, but there was no room. Smaller wire might not handle the current. I've used it once for a very poor weld (my fault, not the machine's) of 18 gauge pipe to a bit thinner than 18 gauge sheet. I tried to do short beads which was a mistake. Should have just done a lot of spots. Had a couple blow-throughs, but over-all the welds needed little strength and can't be seen. I plan to get some practice in a couple months when it warms up (have to weld outdoors). Happy I did the mod, and nice to have the little box when needed.
    "Love 'em all... let God sort 'em out!"

  23. #223
    Join Date
    Jul 2008
    Location
    Long Island
    Posts
    2,973

    Re: Converting 90 amp AC welder to DC

    Quote Originally Posted by California View Post
    Maybe the instructions were for the old blue 90A welders, and you applied them to the current black version?
    The instructions were for the gray version that had no tip contactor, so the tip was always hot, even when the wire wasn’t being pushed.

    That has been superseded by the black Flux 90, which was again superseded by the black Flux 125, which is what I just picked up cheap on CL.

    I can’t speak to the 90 (though everything I read says it is identical to the 125), but mine has a cold tip, so there’s no need for a contactor mod. It also has a nice 120V fan, so no need to mod that either. Still has AC output though, and I'm not even going to bother trying FCAW on AC.

    I went with a 400A 1600V bridge rectifier (I figured that bigger is better, in that I'd NEVER be able to overheat it). I mounted it sideways to a strip of aluminum cut from a pool ladder tread, next to the transformer (with a sufficient gap behind for cooling airflow), plus a 150000mfd cap I had sitting around. I didn't bother with an inductor coil at all. For now, there is no bleeder resistor on the cap (I have one on order), and I've been bleeding down the tip with a light bulb between welding sessions.

    It now welds .030” E71T-11 like a dream. I actually didn't notice ANY spatter whatsoever.

    This is before I made all my connections. I needed to extend the gun wire, but just loosened the clamp on the ground, and pulled it back into the case a foot.
    https://uploads.tapatalk-cdn.com/201...4479328152.jpg

    https://www.amazon.com/gp/product/B0..._title_o03_s00
    https://www.amazon.com/gp/product/B0..._title_o03_s01
    https://www.amazon.com/gp/product/B0..._title_o03_s02
    Last edited by rlitman; 04-11-2019 at 03:33 PM.

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